1. Field of the Invention
The present invention relates to an apparatus for receiving a scrambled signal used in a CATV (cable television) system and a broadcasting satellite (BS) system.
2. Description of the Prior Art
In, for instance, a broadcasting satellite (BS) system and a communication satellite (CS) system, a so-called "pay television" type channel has been introduced. In this pay TV channel, either a picture or a sound is converted into a scrambled signal which is then broadcasted.
When such a pay TV signal is received by a television receiver equipped with a BS tuner, the scrambled signal which has been transmitted from the broadcasting station is decoded by a scrambled signal decoder, so that either the normal picture or the normal sound can be reproduced.
Generally speaking, such a scrambled signal decoder sent from a broadcasting station is connected to a main body of a TV receiver, and a rental fee is charged based on the time during which the scrambled signal decoder is in use.
Then, upon receipt of the scrambled signal, this scrambled signal decoder, and then the decoded picture signal or the decoded sound signal is returned to the TV receiver, so that the decoded picture or sound signal is outputted from a cathode-ray tube or a speaker.
On the other hand, in the above-described TV receiver equipped with the BS tuner, a power source of the TV receiver is independently provided with a power source of the scrambled signal decoder. Only when the scrambled signal is received, this scrambled signal decoder is used with a fee payment, but when other signals than the scrambled signal are received, the power source of the scrambled signal decoder is normally turned OFF.
As a consequence, there are some possibilities that the scrambled signal is received by the TV receiver when the power source for the scrambled signal decoder is turned OFF. In this case, while the scrambled signal is supplied from the TV receiver to the scrambled signal decoder, no signal is outputted from this TV receiver, and therefore no picture is displayed on a cathode-ray tube, nor is sound produced from a speaker.
In such a case, a viewer mistakenly believes that the TV receiver is out of order or subject to a malfunction.